Abstract: In this study, antibacterial substances were extracted and identified from the mycelia of Eurotium cristatum FS-1, and evaluated for antibacterial activity against Pseudomonas putida LP-3. The underlying mechanism was investigated by microscopic observations, LP-3 cell content analysis, and metabolomic analysis. The results showed that the half maximal inhibitory concentration (IC50) of the ethyl acetate extract (FSEAE) from the mycelia of Eurotium cristatum FS-1 on P. putida LP-3 (1 × 104 CFU/mL) was 8 mg/mL. As observed by scanning electron microscopy (SEM), FSEAE destroyed the cell membrane of P. putida LP-3. The K+ content in the culture supernatant of P. putida, the activity of oxidative stress enzymes in the cell metabolic pathway (superoxide dismutase, glutathione peroxidase, and catalase) and the content of malondialdehyde (MDA) were measured, showing that the antibacterial effect of FSEAE mainly in the logarithmic growth period of P. putida LP-3 (8­–16 h). Non-targeted metabonomics was used to analyze FSEAE treated samples and control samples (treated by dimethyl sulfoxide), and a total of 124 metabolites were obtained, of which 30 metabolites were significantly different between the two groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that FSEAE affected the growth and metabolism of P. putida mainly by interfering with the tricarboxylic acid cycle. The results from this study can provide a theoretical reference for the development and utilization of Saccharomyces coronatus and its metabolites.

Key words: Eurotium cristatum; bacteriostatic mechanism; Pseudomonas putida; organic extract; metabolomics analysis